It is known in the pertinent field to apply substances such as polymers, silicates, polysaccharides and derivatives in aqueous and nonaqueous solutions in sufficient amount and in a suitable geometric distribution to a smoking article base wrapping paper, preferably cigarette paper, in order thereby to influence the burning properties of the smoking article wrapping material.
WO-A-03/034845 describes cigarettes having an enhanced propensity to self-extinguish, the cigarette paper having annular zones whose porosity is reduced by the presence of a polymer. The polymers used comprise in particular polyvinyl acetate, partially hydrolysed polyvinyl acetate or polyvinyl alcohol.
U.S. patent application No. 20020129824 discloses a cigarette paper for making low ignition propensity cigarettes comprising a base paper with a plurality of zones of thermoplastic polymer printed on a surface of the paper wherein the plurality of zones of the base paper have Coresta porosities between 0 and 14.9 CU (=Coresta units, 1 CU=1 cm2/cm3*cm3 min at 1 kPa pressure difference, in accordance with the recommended CORESTA [Cooperative Centre for Scientific Research Relative to Tobacco, Paris, France] test method No. 40: Determination of Air Permeability of Materials used as Cigarette Paper, Filter Plug Wrap and Filter Joining Paper including Materials Having an oriented Permeable Zone, October 1994, published in Bulletin 1994-3/4). The thermoplastic polymers used in the patent application comprise hydroxypropylcellulose, ethylcellulose, ethylhydroxyethylcellulose, N-substituted acrylamides, poly(vinyl methyl ether), poly(ethylene oxide), poly(vinyl alcohol), poly(2-ethyloxazoline), methylcellulose ether, cellulose acetate, cellulose acetate phthalate and cellulose acetate butyrate.
WO-A-02/067704 discloses a smoking article wrapping material to which has been applied, in at least one zone, a composition for reducing the permeability of the base wrapping material, the composition comprising a permeability reducing substance, a burn rate retarding substance and a burn rate accelerating substance. The substance reducing the permeability of the base wrapping material is selected in particular from polysaccharides, such as starch, modified starch, starch derivatives, cellulose, cellulose derivatives, chitosan, chitosan derivatives, chitin, chitin derivatives, alginate, alginate derivatives and combinations thereof.
From experience, the porosity of smoking article wrapping paper without zones or in sections where no porosity altering zones have been applied is in a range from 20 to 200 CU, whereas it is typically very low in the applied zones, typically being between 3 and 15 CU depending on the construction of the cigarette. The differences in porosity in the applied zones on the one hand and the base cigarette paper on the other alter the amount and composition of the smoke ingredients compared with a cigarette paper with undiminished porosity, but that must be considered undesirable in the pertinent art. Therefore, cigarette paper having porosities in the zones which are above the previously known level is of particular interest, since in this case the amount and composition of the smoke ingredients would experience a smaller change.